The process of forming semiconductor devices is commonly conducted in substrate processing platforms containing multiple chambers. In some instances, the purpose of a multi-chamber processing platform or cluster tool is to perform two or more processes on a substrate sequentially in a controlled environment. In other instances, however, a multiple chamber processing platform may only perform a single processing step on substrates; the additional chambers are intended to maximize the rate at which substrates are processed by the platform. In the latter case, the process performed on substrates is typically a batch process, wherein a relatively large number of substrates, e.g. 25 or 50, are processed in a given chamber simultaneously. Batch processing is especially beneficial for processes that are too time-consuming to be performed on individual substrates in an economically viable manner, such as for ALD processes and some chemical vapor deposition (CVD) processes.
The ALD platform has a wide range of applications with various requirements and constraints that demands a flexible architecture. Platform requirements include wafer preheating, post cooling, preheat & post cool, throughput from 30 wph (wafers per hour) to 270 wph, high vacuum loadlocks, and numerous other specifications can be a challenge to provide the functionality with low entitlement cost.
ALD batch processing platforms provides standard and active wafer cooling capable loadlocks. The high temperature processes (>450° C.) benefit from wafer preheating prior to being placed on the process chamber susceptor. Currently, room temperature wafers are preheated in the process chamber for as long as 3 minutes. This costs valuable processing time and significantly reduce system throughput for shorter processes.
Current ALD processors have numerous methods to heat and cool single wafers in a loadlock. However, the ALD batch processing platforms can process batches with six wafers or more. Single wafer loadlock cycles are too slow (36 seconds) to the meet the 15 second exchange budget. Therefore, there is a need in the art for apparatus and methods for preheating and post-cooling batches of wafers for batch processing.